Humidifiers for respiratory apparatus

ABSTRACT

A humidifier is configured to humidify a flow of pressurized respiratory gas. The humidifier includes a tub base configured to retain a body of water and a tub lid configured to cover the tub base. The humidifier also includes an inlet passage configured to receive the flow of pressurized respiratory gas and deliver the pressurized respiratory gas to an interior of the humidifier. At least a portion of the inlet passage is configured to float on the body of water retained in the tub base.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.16/243,952, filed Jan. 9, 2019, which is a continuation of U.S.application Ser. No. 13/723,236, filed Dec. 21, 2012, now U.S. Pat. No.10,213,573, which claims priority to U.S. Application No. 61/579,298,filed Dec. 22, 2011, the entire contents being incorporated herein byreference.

FIELD OF THE TECHNOLOGY

The present technology relates to humidifiers for respiratory apparatus,for example humidifiers for respiratory apparatus for treating sleepdisordered breathing (SDB) such as obstructive sleep apnea (OSA).

BACKGROUND OF THE TECHNOLOGY

Respiratory apparatuses commonly have the ability to alter the humidityof the breathable gas in order to reduce drying of the patient's airwayand consequent patient discomfort and associated complications. The useof a humidifier placed between the flow generator and the patient maskproduces humidified gas that minimizes drying of the nasal mucosa andincreases patient airway comfort. In addition in cooler climates, warmair applied generally to the face area in and about the mask is morecomfortable than cold air.

Many humidifier types are available, although the most convenient formis one that is either integrated with or configured to be coupled to therelevant respiratory apparatus. While passive humidifiers can providesome relief, generally a heated humidifier is required to providesufficient humidity and temperature to the air so that the patient willbe comfortable. Humidifiers typically comprise a water tub having acapacity of several hundred milliliters, a heating element for heatingthe water in the tub, a control to enable the level of humidification tobe varied, a gas inlet to receive gas from the flow generator, and a gasoutlet adapted to be connected to a patient conduit that delivers thehumidified gas to the patient's mask.

Typically, the heating element is incorporated in a heater plate whichsits under, and is in thermal contact with, the water tub.

SUMMARY OF THE TECHNOLOGY

One aspect of the technology relates to a humidifier having a reducedheated water volume ensuring faster warm up times and/or less thermalinertia. This allows more accurate and/or faster controllability of thewater temperature with reduced thermal overshoots in the control system.This has advantages if, for example, a climate control feedback systemis used to control humidity output.

Another aspect of the technology relates to a humidifier having areduced air path and thus a more compact humidifier volume for a givenreservoir capacity. In current humidifiers, more dead space is requiredto reduce the risk of water getting into the flow generator when thedevice is not level. For example, the required dead space may be equalto the water volume and the humidifier may be designed to be tilted byat least 90° in any direction, and there must be spare volume for thewater to flow into before it can enter the flow generator. According toa further aspect of the technology, in a bird feeder type humidifierwith a tilt-control system only a thin water layer is heated so the airpath just has to accommodate a relatively small amount of water beforeentering the flow generator in tilt conditions.

Still another aspect of the technology relates to promoting evaporationby providing for the air to flow rapidly, in a relatively thin layerover the water surface. This concept naturally allows a thin, high speedair layer to be designed into the humidifier.

According to an example of the present technology, a tub for ahumidifier comprises an inner tub configured to hold a supply of water;an outer tub configured to receive the inner tub, the outer tubcomprising a bottom and a cavity being formed between the bottom and theinner tub when the inner tub is received in the inner tub; and a valveconfigured to control a flow of the supply of water from the inner tubto the cavity, wherein the valve is closed to prevent the flow when theinner tub is received in a first position in the outer tub and open topermit the flow when the inner tub is received in a second position inthe outer tub.

According to another example of the present technology, a humidifier fora respiratory apparatus, comprises a tub as described in the precedingparagraph and a dock configured to receive the tub. According to a stillanother example, the dock comprises a lid movable between an openposition in which the dock is configured to receive the tub and a closedposition in which the dock is configured to hold the tub. According to astill further example, the lid is configured to move the inner tub fromthe first position to the second position when the lid is moved from theopen position to the closed position. An air lock is formed between thesupply of water and the lid when the lid is in the closed position.

According to another example of the present technology, a tub for ahumidifier comprises a tub base configured to contain a supply of water;a tub lid connectable to the tub base, the tub lid comprising an inletfor a flow of breathable gas and an outlet for a flow of humidifiedbreathable gas; a inlet tube connected to the inlet; and an outlet tubeconnected to the outlet, wherein the inlet tube and the outlet tube areconfigured to float on a surface of the supply of water contained in thetub and prevent a flow of water out of the inlet and/or the outlet ifthe tub is tilted and/or rotated.

According to yet another example of the present technology, a tub for ahumidifier comprises a lid including an inlet for a flow of breathablegas and an outlet for a flow of humidified breathable gas; a bottomchamber configured to contain a supply of water exposed to the flow ofbreathable gas; and at least one intermediate level between the lid andthe bottom chamber, the intermediate level being configured to contain apredetermined amount of water exposed to the flow of breathable gas.

According to still another example of the present technology, ahumidifier comprises a first tub configured to contain a supply of waterand having a first size; a second tub configured to contain a supply ofwater and having a second size different than the first size; and a dockconfigured to receive either the first tub or the second tub, the dockincluding an inlet configured to receive a flow of breathable gas anddirect it into the tub received in the dock and an outlet for a flow ofa humidified flow of breathable gas.

According to another example of the present technology, a tub for ahumidifier is configured to contain a supply of water and comprises aninlet for receiving a flow of breathable gas; an outlet for the flow ofbreathable gas; and a movable vane provided between the inlet and theoutlet, the movable vane being configured to direct a selectable portionof the flow of breathable gas from the inlet to the outlet withoutcontacting a surface of the supply of water.

According to a further example of the present technology, a tub for ahumidifier comprises a top lid portion including an inlet conduit for aflow of breathable gas and an outlet conduit for a humidified flow ofbreathable gas; a middle portion including a top portion having an inlethole configured to receive the flow of breathable gas from the inlet ofthe top lid portion and an outlet hole configured to receive the flow ofhumidified breathable gas; and a bottom portion, wherein the bottomportion and the middle portion form a reservoir for a supply of water,the top portion of the middle portion and the top lid portion forming atop chamber separated from the reservoir, and the inlet hole and outlethole are positioned to prevent water from flowing out of the reservoirinto the top chamber if the tub is tilted or rotated.

According to further examples of the present technology, a respiratoryapparatus comprises a flow generator configured to generate a flow ofbreathable gas and a humidifier as disclosed and described herein. Theflow generator may generate the flow of breathable gas at a pressure of2-30 cm H₂O, typically 8-12 cm H₂O. According to a further example ofthe present technology, a tub for a humidifier includes an adjustablesection configured to expand and retract to increase or decrease avolume of the tub. For example, the tub can be expandable to increasethe volume of the tub by about 10-100%. The tub may further include aninlet for receiving a flow of breathable gas and an outlet for the flowof breathable gas.

The adjustable section may be, for example, a concertina-type section orcollapsible and expandable folds, a sliding section with opposing wallsthat overlap and are configured to slidably move with respect to eachother or any other type of arrangement capable of increasing and/ordecreasing the volume of the tub. In the case of a sliding section, theadjustable section comprises a seal positioned between opposable wallsthat are slidably movable with respect to each other. The seal may beany type of seal such as, for example, an o-ring or an overmold seal.

The tub may further include a locking device to lock the adjustablesection at a particular position. The locking device may be any devicecapable of locking the adjustable section at a particular position suchas, for example, an adjustable length latch. In addition, the lockingdevice may lock the adjustable section at a finite number of discretepositions or at an infinite number of positions so that the tub isexpandable at a finite number of discrete increments or at an infinitenumber of increments.

The tub may also include an inlet tube configured to receive the flow ofbreathable gas, wherein the inlet tube has a length sufficient toprevent water from flowing from the inlet tube to the inlet of the dockif the humidifier is tilted and/or rotated. The inlet tube may beadjustable and configured to expand and contract in combination with thesize of the tub to prevent water from flowing from the inlet tube to theinlet of the dock if the humidifier is tilted and/or rotated.

Other aspects, features, and advantages of this technology will becomeapparent from the following detailed description when taken inconjunction with the accompanying drawings, which are a part of thisdisclosure and which illustrate, by way of example, principles of thistechnology.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the variousexamples of this technology. In such drawings:

FIG. 1 is an exploded assembly view of a humidifier according to anexample of the technology;

FIG. 2 is a cross section view of the humidifier of FIG. 1 with the lidin a closed position and the inner reservoir or tub filled with water;

FIG. 3 is a cross section view of the humidifier of FIG. 1 with the lidin an open position and the inner reservoir or tub empty;

FIG. 4 is a second cross section view of the humidifier of FIG. 1 withthe lid in the closed position;

FIG. 5 is a detailed cross section view of the outer tub or tub base,the inner reservoir or tub, and the lid, with the lid in the closedposition;

FIG. 6 is a cross section view of the bottom of the outer tub or tubbase exposing the primary nozzle, the secondary nozzle, and the tiltcontrol labyrinth of the inner reservoir or tub;

FIG. 7 is a view of the humidifier of FIG. 1 tilted in a firstorientation;

FIG. 8 is a view of the humidifier of FIG. 1 tilted in a secondorientation;

FIG. 9 is a view of the humidifier of FIG. 1 tilted in a thirdorientation;

FIG. 10 is a view of the humidifier of FIG. 1 tilted in a fourthorientation;

FIG. 11 is a view of the humidifier of FIG. 1 tilted in a fifthorientation;

FIG. 12 is a view of a humidifier according to another example of thetechnology;

FIG. 13 is a view of a water feed nozzle, breather tube and tilt controllabyrinth of the humidifier of FIG. 12;

FIG. 14 is a view of an inner reservoir or tub of the humidifier of FIG.12;

FIG. 15 is a detailed view of a valve support of the inner reservoir ortub of FIG. 14;

FIG. 16 is a view of a rocker valve of the humidifier of FIG. 12;

FIG. 17 is a cross section view of the humidifier of FIG. 12 with thelid in an open position and the valve closing the water feed nozzle;

FIG. 18 is a cross section view of the humidifier of FIG. 12 with thelid in a closed position and the valve opening the water feed nozzle;

FIG. 19 is a view of a tub lid including a pair of floating tubes of ahumidifier according to another example of the technology;

FIG. 20 is a view of the tub lid and floating tubes of FIG. 19 and a tubbase;

FIG. 21 is a perspective view of the tub lid and floating tubes of FIG.19;

FIG. 22 is a perspective view of a multi-layer passover humidifieraccording to another example of the technology;

FIG. 23 is a cross section view of the humidifier of FIG. 22;

FIG. 24 is a another cross section view of the humidifier of FIG. 22;

FIG. 25 is still another cross section view of the humidifier of FIG.22;

FIG. 26 is a yet another cross section view of the humidifier of FIG.22;

FIG. 27 is a perspective view of the second intermediate level of thehumidifier of FIG. 22;

FIG. 28 is an exploded assembly view of the humidifier of FIG. 22;

FIG. 29 is another exploded assembly view of the humidifier of FIG. 22;

FIG. 30 is a view of a variable size humidifier according to anotherexample of the technology;

FIG. 31 is a cross section view of the humidifier tub of FIG. 30;

FIG. 32 is a cross section view of another humidifier tub with thehumidifier of FIG. 30;

FIG. 33 is a perspective view of the humidifier tub of FIG. 32 with thehumidifier of FIG. 30;

FIG. 34 is another cross section view of the humidifier tub of FIG. 32with the humidifier of FIG. 30;

FIG. 35 is yet another cross section view of the humidifier tub of FIG.32 with the humidifier of FIG. 30;

FIG. 36 is another cross section view of the humidifier of FIG. 30;

FIG. 37 is a view of a variable size humidifier according to anotherexample of the technology;

FIG. 38 is a view of a flow generator used with the humidifier of FIG.37;

FIG. 39 is an assembly view of the humidifier and flow generator ofFIGS. 37 and 38;

FIG. 40 is a cross section view of the humidifier and flow generator ofFIG. 39;

FIG. 40A is a perspective view of a variable size humidifier tub for thevariable size humidifier of FIG. 37;

FIG. 40B is another perspective view of the humidifier tub of FIG. 40A;

FIG. 40C is a perspective view of another variable size humidifier tubfor the variable size humidifier of FIG. 37;

FIG. 40D is another perspective view of the humidifier tub of FIG. 40C;

FIG. 40E is a side view of the humidifier tub of FIG. 40C;

FIG. 40F is another side view of the humidifier tub of FIG. 40C;

FIG. 40G is a top view of the humidifier tub of FIG. 40C;

FIG. 41 is a cross section view of a humidifier including a tub and acradle;

FIG. 42 is a perspective view of the humidifier of FIG. 41;

FIG. 43 is a front perspective view of the tub of the humidifier of FIG.41;

FIG. 44 is a rear perspective view of the tub of the humidifier of FIG.41;

FIG. 45 is a view of a humidifier according to another example;

FIG. 46 is a cross section view of the humidifier of FIG. 45;

FIG. 47 is a view of the humidifier of FIG. 45 with a lid of the cradlein an open position;

FIG. 48 is a view of the tub of the humidifier of FIG. 45;

FIG. 49 is a rear perspective view of the tub of FIG. 45;

FIG. 50 is a cross section view of the tub of the humidifier of FIG. 45with a flow adjustment mechanism in a first position;

FIG. 51 is a cross section view of the tub of the humidifier of FIG. 45with the flow adjustment mechanism in a second position;

FIG. 52 is a cross section view of the tub of the humidifier of FIG. 45with the flow adjustment mechanism in a third position;

FIG. 53 is a view of elements of the flow adjustment mechanism of FIGS.50-52;

FIG. 54 is a perspective view of a tub base of the tub of the humidifierof FIG. 45;

FIG. 55 is a perspective view of a humidifier according to anotherexample of the technology;

FIG. 56 is an exploded assembly view of the humidifier of FIG. 55;

FIG. 57 is a side view of the humidifier of FIG. 55;

FIG. 58 is a plan view of the humidifier of FIG. 55;

FIG. 59 is a bottom view of the humidifier of FIG. 55;

FIG. 60 is a rear view of the humidifier of FIG. 55;

FIG. 61 is a cross section view of the humidifier of FIG. 55;

FIG. 62 is perspective view of a top lid portion of the humidifier ofFIG. 55;

FIG. 63 is a bottom perspective view of the top lid portion of FIG. 62;

FIG. 64 is rear view of the top lid portion of FIG. 62;

FIG. 65 is a plan view of the top lid portion of FIG. 62;

FIG. 66 is a bottom view of the top lid portion of FIG. 62;

FIGS. 67 and 68 are side views of the top lid portion of FIG. 62;

FIG. 69 is a top perspective view of a middle portion of the humidifierof FIG. 55;

FIG. 70 is a bottom perspective view of the middle portion of FIG. 69;

FIG. 71 is a side view of the middle portion of FIG. 69;

FIG. 72 is a plan view of the middle portion of FIG. 69;

FIG. 73 is a bottom view of the middle portion of FIG. 69; and

FIGS. 74 and 75 are side views of the middle portion of FIG. 69.

DETAILED DESCRIPTION OF ILLUSTRATED EXAMPLES

The following description is provided in relation to several exampleswhich may share common characteristics and features. It is to beunderstood that one or more features of any one example may becombinable with one or more features of the other examples. In addition,any single feature or combination of features in any of the examples mayconstitute additional examples.

In this specification, the word “comprising” is to be understood in its“open” sense, that is, in the sense of “including”, and thus not limitedto its “closed” sense, that is the sense of “consisting only of”. Acorresponding meaning is to be attributed to the corresponding words“comprise”, “comprised” and “comprises” where they appear.

The term “air” will be taken to include breathable gases, for exampleair with supplemental oxygen. It is also acknowledged that the blowersdescribed herein may be designed to pump fluids other than air.

Bird Feeder Type Humidifier

One example of a “bird feeder” type humidifier has a water reservoirfeeding a smaller volume of heated water in the humidifier air paththrough a nozzle. The level of water in the smaller heated volume isdictated by the set height of a nozzle i.e. water flows from thereservoir until the level in the lower heated cavity reaches the nozzle,thus creating an air lock. See, for example, U.S. Pat. No. 7,096,864,the entire contents of which are incorporated herein by reference.

The air lock ensures that the pressure above the water is lower than thepressure outside of the air lock. This lower pressure region is referredto as a vacuum. As water is lost by evaporation, the water level fallsbreaking the air lock which allows more water to flow into the heatedcavity. The water level then rises until the air lock is once againcreated. With one nozzle, the water level can fall a few millimetersbelow the nozzle height as a meniscus maintains the air lock. Once themeniscus can not support the air lock, air can flow into the reservoirand the heated air cavity refills to the set height of the nozzle.

The humidifier of U.S. Pat. No. 7,096,864 has a second, lower depth,nozzle which the water can flow through to maintain the fluid level.This provides more consistent filling of the heated air cavity. With asecond, lower depth, nozzle the pressure head of the reservoir maintainsa constant level of water, dictated by the height of the primary nozzlewithout the level fluctuations present if just a single nozzle is used.The second nozzle controls water flow into the heated cavity and thewater pressure head in the reservoir above maintains a constant liquidlevel, controlled by the primary nozzle, and prevents a meniscus fromforming on the primary nozzle. The water level in the heated cavity istherefore controlled more consistently than with a single nozzle.

A disadvantage with bird feeder type humidifiers is that if they are notlevel then the air lock may be lost allowing water to flow freely intothe heated cavity. This water will then flow into the flow generator ofthe respiratory apparatus and/or the patient tube (i.e. the air deliveryhose or conduit). The water may also “spit out” as the air path may betotally or partially blocked with water.

Another difficulty with current bird feeder type humidifiers is fillingthe humidifier with water. For the bird feeder principle to work thevacuum is required above the water, but this must be removed to fill thewater tank.

Tilt Spill Control

Referring to FIGS. 1-11, a humidifier 2 according to an examplecomprises a cradle 3. The cradle 3 may comprise a heater plate 14,although it should be appreciated that the cradle 3 may include anintegrated heater. The cradle 3 also comprises a lid 16 that may bepivotally connected to the cradle. The cradle 3 may be part of a flowgenerator that is configured to generate a flow of breathable gas at apressure of 2-30 cm H₂O, or the cradle 3 may be separate from and/orconnectable to the flow generator.

The cradle 3 is configured to receive a tub. The tub comprises an outertub or tub base 4 and an inner reservoir or inner tub 6. The innerreservoir or inner tub 6 includes a valve 8 that controls water flowfrom the inner reservoir or inner tub 6 to a cavity 40 that isconfigured to be heated by the heater plate 14 of the cradle 3. Theinner reservoir or inner tub 6 is configured to contain a supply ofwater 20 for humidifying a flow of breathable gas through the humidifier2. The inner reservoir or inner tub 6 is configured to be received inthe outer tub or tub base 4 so that a cavity 40 is provided between theinner reservoir or inner tub 6 and the outer tub 4. The cavity 40 may beheated by the heater plate 14. The bottom 22 of the outer tub 4 may beheat conductive. For example, the bottom 22 may be formed of metal andthe remainder of the outer tub 4 may be formed of, for example, aplastic material.

The valve 8 controls the flow of water 20 from the inner tub 6 to theouter tub 4. The lid 16 of the cradle 3 may be pivoted from the openposition shown in FIG. 3 to the closed position shown in FIG. 2. In theclosed position the lid 16 engages the inner tub 6 as shown in FIG. 5and pushes the inner tub 6 into engagement with the outer tub 4. Asshown in FIG. 5, the lid 16 may include a lid rib or lid projection 36that is configured to engage a seal (not shown) provided in a firstgroove 32 that extends around the perimeter of the top of the inner tub6. The perimeter of the top of the inner tub 6 may also comprise a tubrib or tub projection 38 extending around the perimeter that isconfigured to engage a seal (not shown) provided in a second groove 34that extends around a perimeter of the top of the outer tub 4. The sealsmay be, for example, overmoulded to the inner and outer tubs 6, 4, orthe inner and/or outer tubs 6, 4 may be formed of, for example, flexiblethermoplastic elastomer (TPE). In the closed position of the lid 16shown in FIG. 5, the tub is sealed at the top and at the lid 16 toprevent water from spilling out of the tub from between the inner andouter tubs 6, 4 and between the inner tub 6 and the lid 16.

Referring to FIG. 2, in the closed position of the lid 16, an air lock18 is created between the top surface of the water 20 and the sealed lid16. The air lock 18 creates a vacuum above the water 20 that preventsthe free flow of the water 20 into the cavity 40. The valve 8 seals aprimary or first nozzle 26 and a secondary or second nozzle 28 when thelid 16 is in the open position shown in FIG. 3. When the lid 16 ispivoted to the closed position shown in FIG. 2, the valve 8 is liftedoff the valve seat 30 of the inner tub 6 and water 20 may flow from theinner tub 6 to the cavity 40 between the inner tub 6 and the bottom 22of the outer tub 4. The primary (or first) nozzle 26 maintains aconstant water level in the cavity 40 and the secondary (or second)nozzle 28 ensures a consistent water level by controlling the flow ofwater into the cavity 40.

The valve 8 comprises a valve spring 10 provided on a valve stem 12. Aspring stop 9 is provided between the valve 8 and the valve spring 10.In the open position of the lid 16 shown in FIG. 3, the valve spring 10pushes up the inner tub 6 and the valve 8 is engaged with the valve seat30 (i.e. the valve 8 is closed) and the inner tub 6 may be removed fromthe outer tub 4 for filling with water 20. The inner tub 6 may also befilled with water 20 in-situ (i.e. without being removed from the outertub 4) as the air flow path is sealed off from the water. The force ofthe valve spring 10 is sufficient to maintain the valve 8 closed evenwhen the inner tub 6 is full of water. When the inner tub 6 is filledwith water 20 and placed into the outer tub 4 and the lid 16 is closedas shown in FIGS. 2 and 4, the inner tub 6 is engaged by the lid 16 andpushed down against the bias of the valve spring 10. The valve 8 islifted off of the valve seat 30 and the water 20 may flow through theprimary and secondary nozzles 26, 28 into the cavity 40 until the waterlevel reaches the level of the primary nozzle 26. A flow of breathablegas enters the heated cavity 40 through an inlet tube 42 in the cradle 3and through an inlet aperture 41 and the humidified flow of breathablegas exits through an outer tub outlet 43 of the outer tub 4 incommunication with an outlet tube 44 of the cradle 3.

The inner tub 6 includes a tilt control labyrinth 24 provided on abottom of the inner tub 6 around the primary and secondary nozzles 26,28. Referring to FIGS. 6-11, which illustrate a different tubconfiguration from FIGS. 1-5, when the tub is tilted, water in thecavity 40 flows through an opening 25 in the tilt control labyrinth 24until the tilt labyrinth water level 48 is at a set height of theprimary nozzle 26. When the humidifier 2 is tilted on the inlet end(i.e. with the inlet tube 42 at the bottom) as shown in FIG. 7, thewater cannot flow out of the inlet tube 42 or the outlet tube 44. Thetilt control labyrinth 24 maintains the air lock 18 and prevents thewater 20 in the inner reservoir 6 from emptying into the cavity 40. Thecavity 40 has a volume sufficient to allow water to flow into the cavity40 in all orientations before it can flow out of the inlet tube 42 orthe outlet tube 44.

As shown in FIG. 8, when the humidifier is tilted on its side so thatthe inlet tube 42 is facing down, the tilt labyrinth water level 48 inthe tilt control labyrinth 24 and the cavity water level 46 in thecavity 40 prevent the water from flowing out of the inlet tube 42 andthe outlet tube 44.

When the humidifier is tilted on the outlet end (i.e. with the outlettube 44 on the bottom) as shown in FIG. 9, the tilt labyrinth waterlevel 48 in the tilt control labyrinth 24 and the cavity water level 46in the cavity 40 prevent the water from flowing out of the outlet tube44 and the inlet tube 42. The tilt labyrinth water level 48 in the tiltcontrol labyrinth 24 maintains the air lock 18 in the inner reservoir 6.

When the humidifier is tilted on its side with the inlet tube 42 facingup as shown in FIG. 10, the tilt labyrinth water level 48 in the tiltcontrol labyrinth and the cavity water level 46 in the cavity 40 preventwater from flowing out of the inlet tube 42 and the outlet tube 44. Whenthe humidifier is tilted upside down as shown in FIG. 11, the cavitywater level 46 in the cavity 40 prevents water from flowing out of theinlet tube 42 and the outlet tube 44. Although the humidifier is shownin FIGS. 6-11 in various tilted conditions, it should be appreciatedthat the tilt control labyrinth 24 prevents water flowing into the inletor outlet tubes 42, 44 in positions intermediate to those shown in FIGS.6-11, for example at all positions intermediate the positions shown inFIGS. 7 and 10, and at all positions intermediate the positions shown inFIGS. 8 and 9.

Referring to FIGS. 12-18, a humidifier 50 according to another examplecomprises an inner reservoir or inner tub 56 configured to be receivedin an outer tub or tub base 60. A cavity 55 is provided between theinner tub 56 and the outer tub 60 (see FIGS. 17 and 18). Water stored inthe inner tub 56 may flow through a water feed nozzle 70 provided in theinner tub 56 into the cavity 55. The outer tub 60 may have a heatconductive base or heater plate 64 provided at the bottom of the outertub 60 to heat the water in the cavity 55. A tub seal 75 may be providedbetween the inner tub 56 and the outer tub 60. A lid 52 may be pivotablyconnected to the outer tub 60. A lid seal 54 may be provided on the lid52 and an inner seal 74 may be provided on the inner tub 56. The seals75, 54 and 74 seal the outer tub 60 and the inner tub 56 and the innertub 56 and the lid 52, respectively.

A rocker valve (or rocker arm) 58 is provided in the inner tub 56 tocontrol the flow of water from the inner tub 56 through the water feednozzle 70 into the cavity 55. The rocker valve 58 (or rocker arm)comprises an axle 78 that is engaged with rocker valve supports 76provided in the inner tub 56. The axle 78 may snap into the rocker valvesupports 76 and be removable, for example to clean the rocker valve 58and the inner tub 56. The rocker valve 58 may also include a handle 84to permit the lift and carry of the inner reservoir or inner tub 56 outof the outer tub 60. The handle 84 may also serve as a water levelindicator.

The rocker valve 58 is pivotable in the inner tub 56 about the axle 78.A rocker valve biasing element 80 is provided to the rocker valve 58 tobias the rocker valve 58 into a closed position shown in FIG. 17 whenthe lid 52 is in an open position. It should be appreciated that therocker valve biasing element 80 may be a resilient element that is, forexample, integrally formed with the rocker valve 58, or providedseparately, such as a leaf spring or a coil spring that is provided inthe inner tub 56 for engagement with the rocker valve 58. In the valveclosed position, a valve element 82 of the rocker valve 58 is engagedwith a valve seat 86 in the inner tub 56 to close the water feed nozzle70. When the lid 52 is pivoted from the open position shown in FIG. 17to the closed lid position shown in FIG. 18, the lid 52 engages the top88 of the rocker valve 58 and pivots the rocker valve 58 from the valveclosed position shown in FIG. 17 to the valve open position shown inFIG. 18. In the valve open position shown in FIG. 18, water may flowfrom the inner tub 56 through the water feed nozzle 70 into the cavity55. A flow of breathable gas may enter the cavity 55 through an air flowinlet or inlet tube 62 and the humidified air flow may exit thehumidifier through an outlet tube 66.

The inner tub 56 comprises a breather tube 72 to maintain the air lockbetween the water in the inner reservoir or inner tub 56 and the lid 52.The breather tube 72 also provides for air to travel to the top airpocket portion of the reservoir instead of bubbling through the watervolume, when the air lock is broken to release water into the cavity 55.This may be advantageous as air bubbling through the water volume may benoisy and cause patient discomfort. The inner tub 56 also comprises atilt control labyrinth 68 around the nozzle 70 that prevents water inthe cavity 55 from flowing out through the air flow inlet or inlet tube62 and/or outlet tube 66 in a manner similar to that disclosed withrespect to FIGS. 6-11.

As shown in FIGS. 6 and 13, walled portions are provided surrounding theprimary nozzle 26 or water feed nozzle 70. In FIG. 6, the walled portioncomprises second nozzle 28 and tilt control labyrinth 24. In FIG. 13,the walled portion comprises tilt control labyrinth 68. The walledportions provide a means for trapping water and preventing water fromflowing out, for example when the humidifier is tilted. The walledportions may comprise a plurality of walls, or a singular wall extendingin a generally circular configuration as shown in FIG. 13 to surroundthe water feed nozzle 70. It is envisaged that the walled portions maybe of the same height extending from the bottom of the inner tub 56, oralternatively may have differing heights along its length.Alternatively, the walled portions may extend from the outer tub 60towards the inner tub 56 and surrounding the primary nozzle 26 or waterfeed nozzle 70. Other alternative configurations of walled portions fortrapping water and/or providing tilt protection are also envisaged.

Humidifier with Floating Tubes Tilt Control

Referring to FIGS. 19-21, a humidifier comprises a humidifier tub 90including a tub base 94 and a tub lid 92. The humidifier tub base andtub lid may be similar to the tub base and tub lid disclosed anddescribed in, for example, U.S. 2011/0155132 A1 and U.S. Application61/522,763, filed Aug. 12, 2011, the entire contents of both beingincorporated herein by reference. In the tub 90, the inlet 95 and theoutlet 96 of the tub lid 92 are connected to inlet and outlet tubes 98,100, respectively, which extend inside the tub 90. The inlet tube 98 andthe outlet tube 100 are flexible and/or pivotable, and at least aportion of the inlet tube 98 and the outlet tube 100 are configured tofloat on a surface of the supply of water contained in the tub 90 andprevent a flow of water back through the inlet 95 and/or the outlet 96if the tub 90 is tilted and/or rotated. The inlet tube 98 and the outlettube 100 may have at their opening end, floatable material 97, 99 (e.g.styrofoam), respectively. Alternatively, the entire inlet tube 98 and/oroutlet tube 100 may be formed of a floatable material or may be coupledto floatable material to allow the inlet tube 98 and/or the outlet tube100 to float. When the tub 90 is filled with water, the open ends of theinlet tube 98 and the outlet tube 100 will always stay afloat on thewater surface no matter how the tub 90 is tilted. Accordingly, water isnot able to flow back through the inlet 95 or the outlet 96 and spillinto the flow generator or the air delivery conduit (i.e. the patienttube). In an alternative arrangement only the inlet tube 98 may beconfigured to float on a surface of the supply of water contained in thetub 90 to prevent a flow of water back through the inlet 95 and into theflow generator.

Multi-Layer Passover Humidifier

Referring to FIGS. 22-29, a humidifier 102 comprises a lid 104, at leastone intermediate level, such as a top or first level 106, a second level110, a third level 114, etc, and a bottom level or bottom chamber 118.Multiple intermediate levels may be provided between the lid 104 and thebottom chamber 118, such as 1, 2, 3, 4, 5 or more intermediate levels.The multiple intermediate levels 106, 110, 114 and the bottom chamber118 increase the surface area to increase the humidity output of thehumidifier 102. The humidifier 102 may be powered (i.e. heated) ornon-powered. For example the humidifier may be provided with a lowerpowered heater (e.g. 10W) operated by, for example a battery. Byincreasing the surface area of the water contained by the humidifier102, the humidifier 102 may be smaller than current humidifiers and thusbe more suited for travel. The lid 104, the intermediate levels 106,110, 114 and the bottom chamber 118 may be formed, for example, bymoulding plastic material which would provide a relatively low costhumidifier. The lid 104, the intermediate levels 106, 110, 114, and thebottom chamber 118 may be sealed to each other with, for example,overmoulded seals provided around the perimeters of the lid 104, levelsand bottom chamber 118. The bottom chamber 118 includes a heatconductive material, such as a heat conductive base, to allow the waterwithin the tub 90 to be heated by coupling of a heat conductive base toa heating plate. As shown in FIG. 27, the intermediate levels 106, 110,114 may be designated by indicia 126 and/or may include complementaryengagement features that aid in assembly or prevent re-assembly of thelid 104, and the intermediate levels 106, 110 and 114 in an incorrectconfiguration.

The lid 104 includes an air flow inlet or inlet tube 120 and ahumidified air flow outlet or outlet tube 122. As shown by the arrows inFIG. 24, the flow of breathable gas enters the humidifier 102 throughthe inlet 120 and flows across a surface of water 131 in the first level106, through a first filler conduit 108, across a surface of water 132in the second level 110, through a second filler conduit 112, across asurface of water 133 in the third level 114, through a third fillerconduit 116, and across the surface of the water 134 in the bottomchamber 118. Thus, the conduit of each intermediate level is configuredto direct the flow of breathable gas across the surface of the water ofthe next level. The humidified flow of breathable gas exits thehumidifier through the outlet 122.

In order to fill the humidifier 102 with water, the lid 104 is removedand water is poured into the first level 106. Each intermediate levelmay comprise a grid pattern 128 forming a plurality of grids 130 in eachlevel. The grid pattern 128 and the grids 130 make the humidifier 102fairly tolerant of tipping when filling the humidifier 102 as the wateris locally contained to a degree within each grid 130. Additionalcontainment walls may be provided to contain the water from flowing downthe filler conduits 108, 112, 116 when the humidifier 102 is tilted.

The water poured into the first level 106 continues to fill the grids130 of the first level 106 until the water level reaches the level ofthe first filler conduit 108. As water is continued to be poured intothe first level 106, the additional water flows through the first fillerconduit 108 into the second level 110 until it fills the grids 130 ofthe second level 110 and reaches the level of the second filler conduit112. As more water is added, the water flows through the second fillerconduit 112 and flows into the third level 114. Once the grids 130 ofthe third level 114 are filled and the water level reaches the level ofthe third filler conduit 116, the water flows through the third fillerconduit 116 into the bottom chamber 118. The bottom chamber 118 has acapacity large enough for all of the water in the event that the waterfrom all the preceding intermediate levels, e.g. the first three levels,is spilled into the bottom level. A water level indicator may beprovided at the bottom chamber 118 so the humidifier tub 102 would notbe overfilled as to obstruct air flow passage exiting through the outlet122.

The pressure drop of the flow of breathable gas through the humidifier102 may be modified by adjusting the diameters of the filler conduits108, 112, 116. For example, the pressure drop may be reduced byincreasing the diameter of some or all of the filler conduits. It shouldalso be appreciated that the pressure drop may be varied by changing thenumber of intermediate levels of the humidifier. As shown in FIG. 24, anair gap height 124 may be chosen so as not to have spitting due to ahigh speed air flow.

Humidifier with Variable Size Tubs

Referring to FIGS. 30-36, a humidifier 332 comprises a first tub 336 anda dock 334 configured to receive the first tub 336. The dock 334 may bepart of a flow generator of, for example, a CPAP apparatus or a separatecomponent that is coupled to a flow generator either directly or via aconduit. An air flow dock inlet 338 is connected to the dock 334, and aninlet seal 342 may be provided to seal the connection between the dockinlet 338 and the dock 334. It should be appreciated that the dock inlet338 and the dock 334 may be integrally formed. The first tub 336comprises a first tub inlet tube 335 in the form of, for example, a tubeconduit that is in communication with the dock inlet 338 and sealed tothe dock 334 and the air flow dock inlet 338 by the inlet seal 342. Thedock 334 also includes a dock outlet 340 connected to the dock 334 andan outlet seal 348 that seals the connection. It should also beappreciated that the dock outlet 340 may be integrally formed with thedock 334.

The first tub 336 includes an end inner wall 337 that is opposed to theend of first tub inlet tube 335. The first tub inlet tube 335 directsthe inlet airflow to the end inner wall 337 of the first tub 336 thusdirecting the air to flow across the whole water surface before flowingout a first tub outlet tube 339 that is in communication with the dockoutlet 340 of the dock 334. The first tub inlet tube 335 has a lengththat provides tilt protection to prevent or reduce the amount of waterflowing out of the dock inlet 338, for example into the flow generator,if the humidifier 332 is tilted. The first tub 336 may also comprise alatch 344 that provides a snap connection to the dock 334.

A second tub 346 sized differently from the first tub 336 may beconnected to the dock 334. The second tub 346 may be larger than thefirst tub 336 to enable the second tub 346 to hold more water than thefirst tub 336. The second tub 346 includes a second tub inlet 345similar to the first tub inlet 335 of the first tub 336, but having agreater length. The second tub inlet 345 also directs the inlet air flowagainst the end inner wall 347 of the second tub 346 to direct the airflow across the whole water surface before flowing out the second tuboutlet 349 that is in communication with the dock outlet 340 of the dock334. The second tub inlet 345 of the second tub 346 also provides tiltprotection in the same manner as the first tub inlet 335 of the firsttub 336. The second tub 346 may also comprise the latch 344 forconnecting the second tub 346 to the dock 334.

The inlet and outlet seals 342, 348 may be overmoulded to the dock 334and/or the tubs 336, 346. In the case where the dock 334 is part of aflow generator, the tub 336, 346 may replace an outlet muffler connectedto the flow generator. The first and second tubs 336, 346 may beconfigured to be clipped or snapped into the same position as the outletmuffler. Thus at least one of the first tub 336 and the second tub 346may have a same configuration as the outlet muffler of the flowgenerator. The first tub 336 and the second tub 346 may also include aheater element 350 in the base of the tub to heat the water contained inthe tub.

With the humidifier 332 with variable tub size, the patient or cliniciancan choose to dock a large or smaller sized water reservoir or tub,depending on portability, water usage, and desired size requirements.The components of the humidifier are also easy to mould and/or assemble.The locations of the inlet tubes 335, 345 and the outlets of the tubs336, 346 provide good airflow direction across the surface of the waterand spillback tilt protection. There may be a range of differently sizedtubs available to meet differing humidification and/or portabilityrequirements.

Referring to FIGS. 37-40, a variant of the humidifier includes a tub3736 having a tub inlet 3735 and a tub outlet 3737. As shown in FIGS.37-40, the tub inlet and outlets 3735, 3737 of the tub 3736 arehorizontal which provides easier connection of the tub 3736 to the flowgenerator 3750, and the same face sealing direction is applied for boththe inlet and outlet. The tub 3736 may have a latch 344, such as a snaplatch, configured to releasably connect the tub 3736 to a cradle or dockwhich may be, for example, a flow generator 3750. The tub 3736 may beone of a plurality of tubs of varying size.

The flow generator 3750 may comprise a flow generator outlet 3752 for aflow of breathable gas generated by the flow generator 3750 configuredto be in communication with the tub inlet 3735 of the tub 3736 and ahumidified flow inlet 3754 configured to be in communication with thetub outlet 3737 of the tub 3736. A tubing connector 3756 is configuredto be connected to a delivery tube, hose or conduit configured to beconnected to a patient interface for delivery of the humidified flow ofbreathable gas. The flow generator 3750 may also include a heaterelement 3758 configured to heat the supply of water or liquid in the tub3736.

As shown in FIGS. 39 and 40, the tub 3736 has an end inner wall 3747 todirect the air flow across the whole water surface before flowing outthe outlet 3737. A curved wall or baffle 3749 may also be provided todirect the flow across the water surface.

In another arrangement (see FIGS. 40A-40G) a tub 436 may include anadjustable portion 438 that is configured to be expanded or contractedto adjust the size of the tub 436. The tub 436 may be fixed or locked ina range of different sizes to adjust to the humidification and/orportability needs of the user. For example the tub 436 may include aconcertina-type section or collapsible and expandable folds (FIGS.40A-40B). The concertina-type section and the other portions of the tub436 may be made from the same or different materials. For example, theconcertina-type section may be made from a rigid plastic material or aflexible material such as silicone. In addition, the walls in theconcertina-type section may have a different thickness or the samethickness as the walls of the other portions of the tub 436. Thinnerwalls may increase the expandable capacity of the tub 436.

The adjustable portion 438 may be a sliding portion (FIGS. 40C-40G).When the adjustable portion 438 is a sliding portion, the tub 436 mayinclude an expansion portion 440 and a base portion 442. The expansionportion 440 and the base portion 442 may overlap each other and may beseparated by a gap 444. The gap 444 may serve to minimize wear to theopposing surfaces of the expansion portion 440 and the base portion 442caused by movement between the expansion portion 440 and the baseportion 442. A gap seal 446 may be positioned between the expansionportion 440 and the base portion 442 to prevent liquid from leakingthrough the gap 444. The gap seal 446 may be affixed to and may movewith the expansion portion 440. In addition, the gap seal 446 may be,for example, an o-ring or an overmold seal. The expansion portion 440and the base portion may be made from the same or different materials.

In certain arrangements the tub 436 may be fixed or locked into one of aplurality of sizes by clamping a protrusion or lug into one of a rangeof different recesses or apertures provided on the tub 436. In anotherarrangement an adjustable length latch may fix the tub 436 to form thedifferent size tubs. The tub 436 may be formed of a plastic material ormay include a combination of materials including a plastic material anda flexible material such as silicone. The flexible material may beconfigured to expand and contract.

The adjustable portion 438 may increase the capacity of the tub 436 bybetween about 10-100% (e.g., 20%, 30%, 40% 50%, 60%, 70%, 80%, 90%). Inaddition, the adjustable portion 438 may increase a volume of the tub436 by predetermined discrete increments such as, for example, 5 mL, 10mL, 20 mL, or more. Alternatively, the adjustable portion 438 mayincrease the volume of the tub 436 by an infinite number of increments.Furthermore, the adjustable portion 438 may be a combination of one ormore of the arrangements disclosed above (e.g., a combination of asliding section and a concertina-type section).

In certain arrangements a size of an inlet tube may also be configuredto adjust by expanding and contracting in combination with the size ofthe tub to maintain the tilt protection feature and prevent spillbackinto the flow generator as described above in relation to FIGS. 30 to36.

Humidifier with Mechanical Humidity Control

Referring to FIGS. 41-44, a humidifier 152 comprises a tub 162. The tub162 may be similar to the tubs disclosed and described in WO 2010/031126A1 and U.S. Application 61/522,763, filed Aug. 12, 2011, the entirecontents of both being incorporated herein by reference. The tub 162 maybe placed in a cradle or dock 153. The cradle or dock 153 may have ahinged lid 154 that is pivotable between a closed position (FIG. 41) andan open position (FIG. 42). The hinged or pivotable lid 154 may have anopening 155 and a handle 164 of the tub 162 may extend through theopening 155 when the lid 154 is in the closed position. The handle 164may also include a latch 165 that engages the pivotable lid 154 in theclosed position to releasably secure the pivotable lid 154 in the closedposition. The handle 164 may be resilient to allow the latch 165 to berepeatedly engaged and disengaged with the lid 154 to allow for repeatedopening and closing of the lid 154 and removal and reinsertion of thetub 162 into the cradle or dock 153.

The tub 162 comprises a tub inlet 173 in communication with an air flowinlet 160 of the cradle or dock 153. An inlet seal 170 may be providedaround the inlet aperture 166 to seal with the cradle or dock inlet 160.It should be appreciated that the inlet seal 170 may be overmoulded tothe inlet aperture 166, or to the cradle or dock inlet 160 of the cradleor dock 153, or provided separately between the cradle or dock inlet 160and the inlet aperture 166. The tub 162 may also include an outlet seal158 at the outlet aperture 168 of a tub outlet 175 of the tub 162. Theoutlet seal 158 seals with a cradle or dock outlet 156 of the cradle ordock 153. It should be appreciated that the outlet seal 158 may beovermoulded to the tub 162 and/or the cradle or dock outlet 156 of thecradle 153, or provided separately between the two.

The tub 162 comprises a filling area, or sump, 174 into which water maybe poured to fill the tub 162. A water level indicator 176 may beprovided to indicate the water level in the tub 162. As shown in FIG.41, the water level indicator may be angled. The angled water levelindicator 176 may also direct the inlet air flow across the surface ofthe water in the tub 162. A filling seal 172 may be provided around thefilling area 174 to seal the tub 162 against the tub of the cradle ordock 153. The filling seal 172 prevents water from flowing out of thetub and into the dock 153 if the humidifier is tilted, and also preventsthe inlet air flow from the tub inlet 173 from flowing past the fillingarea 174.

Referring to FIGS. 45-54, a humidifier 178 according to another examplecomprises a tub 190 provided in a cradle or dock 196. The cradle or dock196 includes a hinged lid 180 and the tub 190 includes a handle 186having a latch 185 for releasably retaining the hinged lid 180 in theclosed position (FIGS. 45 and 46).

The tub 190 has a tub inlet 183 in communication with a cradle or dockinlet 182 of the cradle or dock 196. An inlet seal (e.g. an overmouldedseal) 208 is provided between the inlets 182, 183. The tub also has atub seal (e.g. an overmoulded seal) 202 at the outlet that is incommunication with a humidified air flow outlet 184 of the cradle ordock 196. A filling seal 204 is provided around a filling hole 206 toseal against the top of the cradle or dock 196.

A vane 188 is adjustably supported in the tub 190 by a vane adjuster192. The vane adjuster 192 has a screw thread 210 on which the vane 188is adjustably supported as shown in FIG. 53. The position of the vane188 is adjusted by turning the vane adjuster 192 and the vane 188 movesup and down along the screw thread 210 to provide either continuousmovement or to move in discrete amounts. A vane seal 194 is providedbetween the adjuster 192 and the tub 190. The tub inlet 183 has straightsides configured to seal with the movable vane 188. The vane adjuster192 has an alignment mark 198 that indicates the position of theadjuster 192 relative to indicia 200 on the tub 190, and thus theposition of the vane 188 relative to the interior of the tub 190.

Referring to FIG. 50, the vane 188 is in the lowest position in the tub190. The entire air flow in the tub inlet 183 is diverted to the outlet184 without contacting the surface of the water in the tub 190. In FIG.51, the vane is in a middle position and a portion (e.g. 50%) of the airflow from the tub inlet 183 is diverted to the tub outlet 184 and theremainder (e.g. 50%) of the air flow from the tub inlet 183 is divertedby the vane into the tub 190 and across the surface of the water, andthen through the tub outlet 184 of the cradle or dock 196. This providesa portion of the humidifier's output to the patient. Thus, the movablevane 188 is arranged to direct between 0% and 100% of the flow ofbreathable gas from the inlet 183 to the outlet 184 without contacting asurface of the supply of water. The indicia 200 on the tub 190 may belabeled to indicate what portion of the inlet air flow is beinghumidified. FIG. 52 shows the vane 188 in the highest position where theentire air flow from the inlet 183 is diverted into the tub 190 andacross the surface of the water. This provides the entire output of thehumidifier to the patient.

Referring to FIGS. 53 and 54, the tub inlet 183 of the tub 190 may haveflat sides 218 to allow a close seal to the vane 188. Although a smallgap may exist between the tub inlet 183 and the vane 188, the air flowthrough the gap is negligible compared to the flow through the outlet.The tub inlet 183 may also be positioned in the tub 190 to prevent orreduce spillback of water from the tub through the tub inlet 183 intothe cradle or dock inlet 182 of the cradle or dock 196. The filling tube212 may extend through the hole 214 in the vane 188 as the position ofthe vane is adjusted in the tub 190.

The water in the tub 190 may be maintained at a constant temperature.The control of the humidity mechanically through the adjustable vane 188reduces the cost compared to electronic temperature control. It shouldbe appreciated, however, that a low cost PTC heater may be provided tothe humidifier.

The adjustment of the vane 188 allows very fine increments of humidityoutput, for example between 0 (ambient) and 100% humidity can beachieved. Although the drawings show a discrete number of indicia 200indicating the position of the vane 188, it should be appreciated thatthe position of the vane 188 is continuously adjustable within the tub190 and the vane may assume an essentially infinite range of positionswithin the tub. By providing the water at an elevated temperature,bacteria and germs within the water may be eliminated from thehumidified air delivered to the patient.

Humidifier with Two Chambers

Referring to FIGS. 55-75, a humidifier 220 includes a tub that has threeportions. The top lid portion 222 has an inlet conduit 228 for anincoming air flow (e.g. from a flow generator) and an outlet conduit 230for the humidified air flow. Both inlet and outlet conduits 228, 230 arelocated on the top lid portion 222 of the tub. The middle and bottomportions 224, 226 form a reservoir chamber which holds water. The bottomportion 226 may include a heating base, or alternatively it may includea heat conductive base adapted to be in contact with a heating base, totransfer heat to the water held inside the reservoir. The top 232 of themiddle portion 224 and the locations of an air flow inlet hole 234 and ahumidified air flow outlet hole 236 function to keep the water in thereservoir chamber separated from the top chamber 238 where the air flowenters in and out from the inlet and outlet conduits 228, 230.Accordingly, the humidifier 220 provides spill back protection so wateris prevented from spilling back into the inlet and outlet conduits 228,230. Similarly, the humidifier 220 also provides protection againstwater being spilled out if the tub is tilted or bumped or shook.

As shown in FIGS. 70 and 73, a baffle 240 may be provided at the inlethole 234. The baffle may function similarly to the baffle, or wall,disclosed and described in U.S. Application 61/522,763, filed Aug. 12,2011, the entire contents of which are incorporated herein by reference,to direct airflow across the water surface. The humidifier 220 is also asimple design that is easy to mould and assemble.

While the technology has been described in connection with what arepresently considered to be the most practical and preferred examples ofthe technology, it is to be understood that the technology is not to belimited to the disclosed examples, but on the contrary, are intended tocover various modifications and equivalent arrangements included withinthe spirit and scope of the technology. Also, the various examplesdescribed above may be implemented in conjunction with other examples,e.g., aspects of one example may be combined with aspects of anotherexample to realize yet other examples of the technology. Further, eachindependent feature or component of any given assembly may constitute anadditional example. Furthermore, each individual component of any givenassembly, one or more portions of an individual component of any givenassembly, and various combinations of components from one or moreexamples may include one or more ornamental design features. Inaddition, while the technology has particular application to patientswho suffer from OSA, it is to be appreciated that patients who sufferfrom other illnesses (e.g., congestive heart failure, diabetes, morbidobesity, stroke, bariatric surgery, etc.) can derive benefit from theabove teachings. Moreover, the above teachings have applicability withpatients and non-patients alike in non-medical applications.

Table of items listed in figures ITEM NUMBER in FIGURES humidifier orhumidifier tub 2, 50, 102, 152, 178, 220, 332 cradle 3 outer tub or tubbase 4, 60 inner reservoir or inner tub 6, 56 tub 6 valve 8 spring stop9 valve spring 10 valve stem 12 heat conductive base or heater plate 14,64 lid 16, 52, 154, 180 air lock 18 water 20, 131, 132,, 133, 134 bottom22 tilt control labyrinth 24 opening 25 primary nozzle or first nozzle26 secondary nozzle or second nozzle 28 valve seat 30 first groove 32second groove 34 lid rib or lid projection 36 tub rib or tub projection38 cavity 40, 55 inlet aperture 41 inlet tube 42, 62, 98,120 outer tuboutlet 43 outlet tube 44, 64, 100, 122 cavity water level 46 tiltlabyrinth water level 48, 68 lid seal 54 rocker valve or rocker arm 58water feed nozzle 70 breather tube 72 inner seal 74 tub seal 75 rockervalve supports 76 axle 78 rocker valve biasing element 80 valve element82 handle 84 valve seat 86 top (of rocker valve) 88 Humidifier tub ortub 90, 436, 3736 tub lid 92 tub base 94 inlet or air flow inlet 95, 120outlet 96, 122 floatable material 97, 99 lid 104 intermediate levels106, 110, 114 first level 106 first filler conduit 108 second level 110second filler conduit 112 third level 114 third filler conduit 116bottom chamber 118 air gap height 124 indicia 126 grid pattern 128 grid130 dock or cradle 334, 153 first tub inlet tube 335 first tub 336 endinner wall 337, 3747 dock inlet 338 dock outlet 340 inlet seal 342 latch344, 3744 second tub inlet 345 second tub 346 outlet seal 348 second tuboutlet 349 heater element 350, 3758 lid 154 opening 155 cradle or dockoutlet 156 outlet seal 158 cradle or dock inlet 160 tub 162 handle 164latch 165 inlet aperture 166 outlet aperture 168 inlet seal 170 fillingseal 172 tub inlet 173 filling area or sump 174 tub outlet 175 waterlevel indicator 176 cradle or dock inlet 182 tub inlet 183 tub outlet184 latch 185 handle 186 vane 188 tub 190 vane adjuster 192 seal 194dock 196 alignment mark 198 indicia 200 tub seal 202 filling hole 206inlet seal 208 screw thread 210 filling tube 212 hole 214 flat sides 218top lid portion 222 middle portion 224 bottom portion 226 inlet conduit228 outlet conduit 230 top (of middle portion) 232 inlet hole 234 outlethole 236 top chamber 238 baffle 240 tub inlet 3735 tub outlet 3737baffle 3749 flow generator 3750 flow generator outlet 3752 humidifiedflow inlet 3754 tubing connector 3756 heating element 3758 adjustableportion 438 expansion portion 440 base portion 442 gap 444 gap seal 446

What is claimed is:
 1. A tub for a humidifier, comprising: an inner tubconfigured to hold a supply of water; an outer tub configured to receivethe inner tub, the outer tub comprising a bottom, and a cavity beingformed between the bottom and the inner tub when the inner tub isreceived in the inner tub; and a valve configured to control a flow ofthe supply of water from the inner tub to the cavity, wherein the valveis closed to prevent the flow when the inner tub is received in a firstposition in the outer tub and open to permit the flow when the inner tubis received in a second position in the outer tub.
 2. A tub according toclaim 1, wherein the inner tub comprises a first nozzle configured tomaintain a constant level of water in the cavity and a second nozzleconfigured to control the flow into the cavity.
 3. A tub according toclaim 1, wherein the valve comprises a biasing element configured tomaintain the valve closed in the first position and to close the valvewhen the inner tub moves from the second position to the first position.4. A tub according to claim 3, wherein the biasing element comprises aspring.
 5. A tub according to claim 4, wherein the spring is integrallyformed with the valve.
 6. A tub according to claim 1, wherein the valveis pivotably mounted in the inner tub.
 7. A tub according to claim 6,wherein the valve comprises a rocker arm.
 8. A tub according to claim 7,wherein the rocker arm comprises a handle configured to remove the innertub from the outer tub.
 9. A tub according to claim 1, wherein the innertub comprises a labyrinth that prevents the supply of water fromemptying from the inner tub when the inner tub is tilted and/or rotated.10. A tub according to claim 1, wherein the inner tub comprises abreather tube extending from below a top of the inner tub to the cavity.11. A humidifier for a respiratory apparatus, comprising: a tubaccording to claim 1; and a dock configured to receive the tub.
 12. Ahumidifier according to claim 11, wherein the dock comprises a lidmovable between an open position in which the dock is configured toreceive the tub and a closed position in which the dock is configured tohold the tub.
 13. A humidifier according to claim 12, wherein the lid isconfigured to move the inner tub from the first position to the secondposition when the lid is moved from the open position to the closedposition.
 14. A humidifier according to claim 11, wherein the dockcomprises a heater element configured to heat the cavity.
 15. Ahumidifier according to claim 12, wherein an air lock is formed betweenthe supply of water and the lid when the lid is in the closed position.16. A tub for a humidifier, comprising: a tub base configured to containa supply of water; a tub lid connectable to the tub base, the tub lidcomprising an inlet for a flow of breathable gas and an outlet for aflow of humidified breathable gas; an inlet tube connected to the inlet;and an outlet tube connected to the outlet, wherein at least a portionof the inlet tube and the outlet tube are configured to float on asurface of the supply of water contained in the tub and prevent a flowof water back through the inlet and/or the outlet if the tub is tiltedand/or rotated.
 17. A tub according to claim 16, wherein the inlet tubeand the outlet tube each comprise floatable material at ends oppositethe inlet and outlet of the tub lid.
 18. A tub for a humidifier,comprising: a lid including an inlet for a flow of breathable gas and anoutlet for a flow of humidified breathable gas; a bottom chamberconfigured to contain a supply of water exposed to the flow ofbreathable gas; and at least one intermediate level between the lid andthe bottom chamber, the intermediate level being configured to contain apredetermined amount of water exposed to the flow of breathable gas. 19.A tub according to claim 18, wherein the intermediate level includes aconduit configured to allow a flow of water from the at least oneintermediate level to another intermediate level or the bottom chamberwhen water supplied to the at least one intermediate level exceeds thepredetermined amount.
 20. A tub according to claim 19, wherein theconduit is configured to direct flow of breathable gas from the at leastone intermediate level to another intermediate level or the bottomchamber.